Bacteria belonging to the genus Bifidobacterium (hereinafter, referred to as “bifidus bacteria”) are major bacteria in the human intestinal bacterial flora, and are known to have favorable effects for human health, such as regulation of the intestinal function including improvement in constipation or diarrhea symptoms, suppression of increase of the serum cholesterol, immune activating effect, and the like. Many commercial products of Bifidus bacteria are available in forms of various fermented milk drinks and foods or live bacterial preparations, establishing a firm market. In particular, the fermented milk drinks and foods containing bifidus bacteria have favorable taste and are fit for continuous ingestion of bifidus bacteria.
With recent progress on the study of the effectiveness of bifidus bacteria, it was found that the bifidus bacteria have an anti-ulcer effect; for example, it has been reported that 3 species of Bifidobacterium breve YIT 4014, Bifidobacterium breve YIT 4043 and Bifidobacterium bifidum YIT 4007 (FERM BP-791) show an anti-ulcer effect in a rat model with ulcer induced by acetic acid (non-patent document 1). In addition, it has been reported that by administering Bifidobacterium bifidum YIT 4007 in dried powder form, the condition of patients suffering from gastric ulcer or duodenum ulcer is improved and Helicobacter pylori disappear from the gastric mucosa (non-patent document 2). Thus, utilization of the bifidus bacteria has been expected as a preventive or therapeutic agent for infection with Helicobacter pylori or as a preventive or therapeutic agent for gastritis, gastric ulcer and duodenum ulcer. Further, it has been reported that the effect of the above-mentioned Bifidobacterium bifidum YIT 4007 increases in accordance with the increase in the viable cell count to be administered (non-patent document 3). In order to make effective use of the pharmacological action of Bifidobacterium bifidum YIT 4007, it is necessary to allow as many live cells as possible to reach the stomach and intestinal tract.
The bifidus bacteria including Bifidobacterium bifidum YIT 4007 are sensitive to oxygen since they are obligatory an aerobes; particularly, when preserved under aerobic condition, a problem arises that they are rapidly reduced in the viable cell count; therefore, it was difficult to administer the sufficient number of bifidus bacteria.
In order to solve this problem, an attempt is being made to make use of various components for improving the survivability in preservation, such as, vegetable juice of pumpkin, cucumber, etc., pyruvic acid, reduced-type glutathione (patent document 1), glycerol, xylitol, etc. (patent document 2), lactitol (patent document 3), and the like. The addition of these components, however, involves problems such as increase in the production cost, decrease in taste, and the like and thus cannot be readily applied. Another attempt is being made to place a fermented product containing a bifidus bacterium in a vessel composed of oxygen-impermeable wrapping material to completely block contact with oxygen. However, such vessel with perfect oxygen-impermeability has not yet been provided, and further there is a problem that materials having low oxygen-permeability are poor in molding flexibility. Moreover, when a composite material is used for a vessel composed of low oxygen-permeable material, problems arise such as treatment of its waste is complicated, the vessel is per se expensive and the like, and thus there is much limitation in its utilization.
It is considered, accordingly, that an ultimate solution for improving the survivability of the bifidus bacteria in fermented milk drinks and foods etc., is to create a strain of bifidus bacteria having high survivability even in aerobic condition; as examples of such bacterial strains, Bifidobacterium breve YIT 10001 (FERM BP-8205)(patent document 4), Bifidobacterium breve SBR3212 (FERM P-11915) (patent document 5), Bifidobacterium bifidum YIT 4002 (FERM BP-1038) (patent document 6), and the like are already been reported.
These bifidus bacteria having high survivability in aerobic condition, however, exhibited much lower activity of killing Helicobacter pylori and antiulcer activity compared to Bifidobacterium bifidum YIT 4007. Such strain which has high survivability even in aerobic condition and exhibits an activity of killing Helicobacter pylori has not yet been created, and it has been difficult to deliver the sufficient number of live cells for expressing an anti-ulcer effect into the stomach or intestinal tract.
Patent document 1: JP-A-2003-250528
Patent document 2: JP-A-11-137172
Patent document 3: Japanese Patent No. 3261571
Patent document 4: WO 03/040350 International Published Pamphlet
Patent document 5: Japanese Patent No. 2922013
Patent document 6: JP-B-61-19220
Non-Patent document 1: The Japanese Society of Carbohydrate Research, 16th Carbohydrate Symposium, Pamphlet, 24-25 (1994)
Non-Patent document 2: Jpn Pharmacol Ther Vol. 22, No. 11, 253-256 (1994)
Non-Patent document 3: Functional Foods and Pharmacological Nutrients Vol. 2, No. 3, 203-213 (2005)